Abstract

Background The high prevalence of children's asthma symptoms, worldwide, is unexplained. We examined the relation between maternal pre-pregnancy
weight and body mass index (BMI), and asthma symptoms in adolescents.

Methods Data from 6945 adolescents born within the Northern Finland Birth Cohort 1986 were used. Prospective antenatal and birth
outcome data, including maternal pre-pregnancy weight and BMI, and asthma symptoms in adolescent offspring at age 15–16 years,
were employed. Logistic regression analyses were performed to examine the associations between relevant prenatal factors and
asthma symptoms during adolescence.

Results Current wheeze (within the past year) was reported by 10.6% of adolescents, and physician-diagnosed asthma by 6.0%. High
maternal pre-pregnancy BMI was a significant predictor of wheeze in the adolescents (increase per kilogram per square metre
unit; 2.7%, 95% CI 0.9 to 4.4 for ever wheeze; 3.5%, 95% CI 1.3 to 5.8 for current wheeze), and adjusting for potential confounders
further increased the risk (2.8%, 95% CI 0.5 to 5.1; 4.7%, 95% CI 1.9 to 7.7, respectively). High maternal pre-pregnancy weight,
in the top tertile, also significantly increased the odds of current wheeze in the adolescent by 20% (95% CI 4 to 39), and
adjusting for potential confounders further increased the risk (OR=1.52, 95% CI 1.19 to 1.95). Results were similar for current
asthma. Furthermore, these significant associations were observed only among adolescents without parental history of atopy
but not among those with parental history of atopy.

Conclusions The association demonstrated here between maternal pre-pregnancy overweight and obesity, and asthma symptoms in adolescents
suggests that increase in asthma may be partly related to the rapid rise in obesity in recent years.

Footnotes

SPP and AR contributed equally to this work.

Funding The study was supported by the grants from the University of Oulu, Finland; Oulu University Hospital, Finland; the Academy
of Finland; the European Commission (Framework 5 award QLG1-CT-2000-01643), and by Medical Research Council, UK. Dr Rodriguez
received support from VINNMER (P32925-1).

Competing interest None declared.

Patient consent Obtained.

Ethics approval This study was conducted with the approval of the ethics committee of Northern Ostrobotnia Hospital District.